Protective Effects of Caffeine on Chronic Hypoxia-Induced Perinatal White Matter Injury Stephen A. Back, MD, PhD, 1,2 Andrew Craig, BS, 1 Ning Ling Luo, MD, 1 Jennifer Ren, 1 Ravi Shankar Akundi, PhD, 3 Ivy Ribeiro, MD, 3 and Scott A. Rivkees, MD 3 Objective: Periventricular white matter injury (PWMI) is the major cause of cerebral palsy and cognitive impairment in pre- maturely born infants. PWMI is characterized by reductions in cerebral myelination and cerebrocortical volumes and is associ- ated with secondary ventriculomegaly. In neonatal rodents, these features of PWMI can be induced by rearing in chronic hypoxia or by activation of A1 adenosine receptors. We determined: (1) whether altered maturation or development of one or more oligodendrocyte (OL) lineage stages plays a role in the pathogenesis of the myelination disturbances associated with exposure to chronic hypoxia, and (2) whether blockade of A1 adenosine receptor action with the adenosine antagonist caffeine can prevent hypoxia-induced white matter injury. Methods: Ventriculomegaly and reduced cerebral myelination were generated in mice reared in hypoxia (10% oxygen) from postnatal days 3 (P3) through 12. Results: Hypomyelination was related to abnormal OL lineage progression and a reduction in the OL progenitor pool. Myeli- nation was enhanced and ventriculomegaly reduced in hypoxia-exposed neonatal pups treated with caffeine from P3 to P12. Interpretation: These observations support that hypoxia inhibits OL maturation and that caffeine administration during early postnatal development may have utility in the prevention of PWMI. Ann Neurol 2006;60:696 –705 In recent decades, advances in neonatal intensive care have been accompanied by a marked increase in the survival of very low birth weight infants (1.5kg). However, this improved survival has been accompanied by increasing recognition of long-term neurological deficits. 1 Periventricular white matter injury (PWMI) is the major form of brain injury and the leading cause of chronic neurological disability in survivors of prema- ture birth. 2,3 In preterm survivors, PWMI manifests as cerebral palsy in up to 25%. 4 By school age, cognitive and learning disabilities are identified in about half of all preterm survivors. 5 Chronic PWMI includes a spectrum of cerebral pa- thology that includes reduced cerebral myelination, lower cerebrocortical volumes, and secondary ventricu- lomegaly. 6,7 Whereas PWMI was previously dominated by focal cystic necrotic injury (periventricular leukoma- lacia), recent neuroimaging findings support that periventricular leukomalacia is now rarely seen. Rather, a strong predilection for focal, multifocal, or diffuse noncystic lesions that disrupt myelination is emerging. 2 Consistent with these myelination disturbances, pro- nounced depletion of premyelinating oligodendrocyte (OL) stages occurs in early PWMI pathogenesis. 8 Four successive stages of the OL lineage are defined by the expression of OL lineage–specific markers. 7,9 These are early OL progenitors (NG2 + , Olig2 + , PDGFR + , O4 - ), pre-OLs/late OL progenitors (O4 + O1 - ), im- mature OLs (O4 + O1 + ), and mature OLs (MBP + ). The pre-OL coincides with the high-risk period for PWMI 10 and is selectively targeted by oxidative stress and hypoxia-ischemia. 11,12 Hypoxia-ischemia is a significant cause of PWMI 13,14 that is seen both in utero and during neo- natal intensive care. In neonatal rodents exposed to hypoxia, a PWMI-like phenotype occurs that includes ventriculomegaly, reduction in white and gray matter volumes, and reduced myelin basic protein (MBP) ex- pression. 15,16 Of the possible humoral mediators of hy- poxic injury, the nucleoside adenosine may play an im- From the Departments of 1 Pediatrics and 2 Neurology, Oregon Health & Science University, Portland, OR; and 3 Department of Pediatrics, Yale University School of Medicine, New Haven, CT. Received Apr 18, 2006, and in revised form Aug 2. Accepted for publication Sep 12, 2006. This article includes supplementary materials available via the Inter- net at http://www.interscience.wiley.com/jpages/0364-5134/supp- mat Published online Oct 16, 2006, in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/ana.21008 Address correspondence to Dr Rivkees, Department of Pediatrics, Yale University School of Medicine, P. O. Box 208081, 464 Con- gress Ave., New Haven, CT 06520. E-mail: scott.rivkees@yale.edu 696 © 2006 American Neurological Association Published by Wiley-Liss, Inc., through Wiley Subscription Services